Abstract: This invention relates to marking instruments having a uniquely configured nib assembly. The nib assembly comprises an elongated nib, a tip adapter having a first bore and second bore formed therein, the first bore open to the proximal end of the adapter and the second bore open to the distal end of the adapter. A sleeve extends into the first bore and is retained therein. The sleeve has an opening formed along the length thereof with the nib extending through the opening and beyond the distal end of the adapter. The opening and the second bore of the adapter are configured such that the nib is prevented from being pushed back up into the assembly.